# Mean

Mean is an average of the given numbers: a calculated central value of a set of numbers. In simple words, it is the average. It’s also the meanest because it takes the most math to figure it out.  Measures of central tendency, or averages, are used in a variety of contexts and form the basis of statistics. To calculate the arithmetic mean of a set of data we must first add up (sum) all of the data values (x) and then divide the result by the number of values (n). Since ∑ is the symbol used to indicate that values are to be summed (see Sigma Notation) we obtain the following formula for the mean (x̄).

x̄=∑ x/n.

Central tendency is the statistical measure that recognises a single value as representative of the entire distribution. It strives to provide an exact description of the whole data. It is the unique value that is the which represents collected data. The mean, median and mode are the three commonly used measures of central tendency. Here we will discuss about the mean value and its types.

In the case of a discrete probability distribution of a random variable X, the mean is equal to the sum over every possible value weighted by the probability of that value; that is, it is computed by taking the product of each possible value x of X and its probability P(x), and then adding all these products together.

## Types of Mean

There are majorly three different types of mean value which you will be studying in statistics.

1. Arithmetic Mean
2. Geometric Mean
3. Harmonic Mean

### Arithmetic Mean

When you add up all the values and divide by the number of values it is called Arithmetic Mean. To calculate, just add up all the given numbers then divide by how many numbers are given.

Example: What is the mean of 3, 5, 9, 5, 7, 2?

Now add up all the given numbers:

3 + 5 + 9 + 5 + 7 + 2 = 31

Now divide by how many numbers provided in the sequence:

316= 5.16

### Geometric Mean

The geometric mean of two numbers x and y is xy. If you have three numbers x, y, and z, their geometric mean is 3xyz.

$\large Geometric\;Mean=\sqrt[n]{x_{1}x_{2}x_{3}…..x_{n}}$

Example: Find the geometric mean of 4 and 3 ?

Geometric Mean =$\sqrt{4 \times 3} = 2 \sqrt{3} = 3.46$

### Harmonic Mean

The harmonic mean is used to average ratios. For two numbers x and y, the harmonic mean is 2xy(x+y). For, three numbers x, y, and z, the harmonic mean is 3xyz(xy+xz+yz)

$\large Harmonic\;Mean (H) = \frac{n}{\frac{1}{x_{1}}+\frac{1}{x_{2}}+\frac{1}{x_{2}}+\frac{1}{x_{3}}+……\frac{1}{x_{n}}}$

$\large X_{rms}=\sqrt{\frac{x_{1}^{2}+x_{2}^{2}+x_{3}^{2}….x_{n}^{2}}{n}}$
$\large \frac{(x_{1}^{2}+x_{2}^{2}+….+x_{n}^{2})}{(x_{1}+x_{2}+…..x_{n})}$